You do not need to work on yourself forever.
Eating healthy and staying fit are one thing but if you consistently focus on improving yourself or becoming your best self, you forget to acknowledge and accept who you have become so far. You lose appreciation for the energy and time taken to become the person you are today. You must first love yourself before accepting who you are which cannot be done until you are comfortable admitting how far you have come.
We tend to focus our energy on that perfect image of someone we seen in a magazine or an instagram profile. This obsessiveness can become destructive as this is not who you are, it is someone else and you can cannot physically become someone else. Instead, you become a better version of yourself. Self-improvement is achievable, becoming someone else is not.